Answer:
![6y^2i√(6)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/vxte4y51by9lsfv9ru2whh3vaoggcw47cu.png)
Explanation:
For this exercise it is important to remember the following property:
![\sqrt[n]{a^n}=a^{({(n)/(n))}}=a](https://img.qammunity.org/2021/formulas/mathematics/middle-school/zv4cdvo2rwpz39zavjf7pe2hy0ioybfyps.png)
Then, given the expression:
![√(-216y^4)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/fxelqvdynwfze8iyz28z6sm3lolyx31ebm.png)
You can follow these steps in order to simplify it:
1. Descompose 216 into its prime factors:
![216=2*2*2*3*3*3](https://img.qammunity.org/2021/formulas/mathematics/middle-school/a0cnl6uaw1uns7cq8vaxgsii0h941vbdts.png)
2. The Product of powers property states that:
![(a^m)(a^n)=a^((m+n))](https://img.qammunity.org/2021/formulas/mathematics/middle-school/ibgegqo5sxi73v76bxyw47jme7rlhzjyeh.png)
Then:
![216=2^2*2*3^2*3](https://img.qammunity.org/2021/formulas/mathematics/middle-school/fai88hejl422br8i8h490h6ndw69vcbimv.png)
3. Now you can substitute:
![=√(-2^2*2*3^2*3*y^4)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/v88ke7t4mqlf26r65kjes3yc5wucofjvgm.png)
4. Finally, substituting
and simplifying, you get:
![=2*3*y^2i√(2*3)=6y^2i√(6)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/vcclwlc3qqhd48jpb1ptz73z6kiqps8t4a.png)